Variable stroke connecting rod



- 1939- J. DUSEVOIR EI'AL I 2, 80

VARIABLE STROKE CONNECTING ROD Filed Jan. 5, 1938 INVENTORS JULIUS Dose VOIR Gxeess ST QLIN ELM/ BY ATTORNEY.

Patented Oct. 3, 1939 VARIABLE STROKE CONNECTING non Julius Dusevoir, San Leandro, and George Sterling Edwards, San Francisco, Calif.

Application January 3, 1938, Serial No. 183,142

1 Claim. (Cl. 74-4500) This invention relates particularly to a connecting rod construction, the stroke of which will vary automatically because of variable reciprocating forces in the apparatus in which the Fig. 6 is a section taken through Fig. 5 on the line 6-6.

Fig. '7 is a section taken through the crank throw and eccentric and illustrating mechanical 5 connecting rod is used. means for locking the eccentric in a set position. 5

An object of the invention is to provide an Fig. 8 is an enlarged cross section taken automatic variable stroke connecting rod for use through a throw of the crank shaft, showing in engines, pumps, compressors and other enhydraulic means for locking the connecting rod gines utilizing connecting rods, for the purpose eccentrically. in a set position.

10 of effecting higher volumetric efficiency in the The construction and function of the conven- 10 engine; a more complete scavenging operation tional type of set stroke connecting rod as used than could be accomplished with a set stroke in engines, compressors, pumps and the like, is connecting rod; to increase the compression proso well known further explanation thereof will portionately to the engine speed due to variable be omitted herein.

reciprocating forces; and to reduce detonation. In our invention we have provided a ccnnect- 15 A still further object of the invention is to ing rod i, having a piston 2 pivotally mounted provide a connecting rod which has interposed on one end thereof and at its lower end the between the body thereof and the throw of the connecting rod is provided with the usual comcrank shaft to which it is connected, a rotatplementary flanges 3 and 4 for attachment to able eccentric, whereby rotation of the eccenthe throw 5 of a crank shaft. Between the 20 tric, due to the reciprocating force applied to crank shaft throw 5 and the flanges 3 and 4 the connecting rod, will lengthen or shorten the I have provided an eccentric 6, the outer cirstroke of the connecting rod in direct ratio to cumference of which is eccentric relative to the the speed at which the connecting rod recipcenter axis of the crank throw 5. A series of rocates. rollers are interposed between the eccentric 25 Other objects and advantages are to provide 6 and the connecting rod flanges 3 and 4, and a variable stroke connecting rod that will be similar rollers 8 are interposed between the ecsuperior in point of simplicity, inexpensiveness of centric 6 and the crank shaft throw 5. Plates construction, positiveness of operation, and fa- 99 are provided on opposite faces of the flanges cility and convenience in use and general efii- 3 and 4 to hold the eccentric 6 and bars I and 30 ciency. 8 in position within the flanges 3 and 4 of the In this specification and the annexed drawconnecting rod. For ease of installation on the ing, the invention is illustrated in the form concrank shaft, the eccentric 6 may be split on a sidered to be the best, but it is tobe understood medial line into two parts, and the aforesaid 5 that the invention is not limited to such form, parts joined together with dowels or other alignbecause it may be embodied in other forms; and ing mediums. it is also to be understood that in and by the In operation a connecting rod equipped with claim following the description, it is desired to our eccentric connection between it and the cover the invention in whatsoever form it may crank shaft, will cause the said connecting rod 40 be embodied. to have a stroke which, under some conditions, 40

In the accompanying drawing: will exceed its normal length of stroke by the Fig. 1 represents a side elevation, partly in amount of the eccentricity vested in the eccensection, having a crank shaft connection contric 6. Where the pressure forces applied to the structed in accordance with my invention. piston are relatively nominal and the rate of Fig. 2 is a front elevation of Fig. 1. reciprocation of the connecting rod is relatively 45 Fig. 3 is a side elevation similar to Fig. 1, slow, then the connecting rod would assume the showing the connecting rod eccentric in a position indicated in Fig. 4, and would function lengthened position. to all intents and purposes as does a set stroke Fig. 4 is a view similar to Fig. 3 showing the connecting rod. Under slightly modified condiconnecting rod eccentric in the shortened potions, to wit, an increase in the speed of recip- 50 sition. rocation, the eccentric 6 is thrown by centrifu- Fig. 5 is an enlarged cross section taken gal force upon the axis of the throw of the crank through a throw of the crank shaft, showing shaft, and will assume the position indicated mechanical means for turning the connecting in Fig. 3 wherein the length of stroke of the conrod eccentric. necting rod is increased by the amount of ec- 55 plates II-II of the crank shaft.

ens the stroke of the connecting rod by the distance indicated by the piston shown in Figs. 3 and 4. Where the speed of reciprocation of the connecting rod causes the eccentric to be automatically rotated around the throw of the crank shaft and the length of the stroke of the connecting rod to be increased, it is obvious that the piston will be moved higher in the cylinder of the piston, causing a greater compression effeet to be given to the combustible mixture, thereby resulting in a highly volumetric efficiency of the engine, and also thereby more completely scavenging the engine cylinder on the exhaust stroke of the engine, and thereby also reducing the detonation in the engine on the firing stroke. Likewise, similar increases in efiiciency will be obtained where the variable stroke connecting rod is used in compressors and pumps.

While the illustrations which we have noted above may be extreme situations encountered in engine operation, the nature of the freely rotatable eccentric is such that it will automatically compensate itself to the running conditions of the engine and irrespective of the pressure conditions in the engine cylinder or the speed of rotation of the crank shaft, will automatically adjust itself to add extra efliciency to the engine operation where the operating conditions will permit that result to be accomplished.

In Figs. 1 through 4 inclusive, we have illustrated the eccentric as being of a split form, although it is to be considered within the scope of the invention that the eccentric be of unbroken form, and would be mounted on a throw of a crank shaft of the assembly type.

In Figs. 5 and 6, we have illustrated a portion of a crank shaft showing a hollow throw I I] connected at its opposite ends to the parallel cheek The hollow interior of the crank throw I forms a cylinder I2 which would be capped or closed at its opposite ends. The cylinder I2 has a plunger I3 reciprocatingly confined therein and the outer periphery of the plunger has spirally disposed teeth I4 cut therein. An eccentric I5 is mounted around the throw III and the end of the connecting rod I6 is mounted around the eccentric I5. Roller bearings I1 and I8 are interposed between the crank throw and eccentric, and the eccentric and connecting rod. The inner face of the eccentric I5 is provided with a gear segment I9 thereon which extends through a slot 20 in the throw ID. The said gear segment meshes with the spiral teeth I4 on the plunger I3. Passages 2I are drilled in the cheek plates I II I and through the wall of the throw l0, and all of said passages are connected to a fluid pressure system. A by-pass connection 22 connects the passage 2| with the cylinder I2 on one side of the plunger I3. When fluid under pressure is directed into the cylinder I2 against the plunger I3, said plunger is caused to move axially in the cylinder I2 and the spiral teeth I4 on said plunger, by reason of their meshing engagement with the gear segment l9, cause said segment to rotate and in turn causes the eccentric l5 to be partially rotated around the axis of the throw I0. Rotation of the eccentric in this manner, will thus effect the length of the stroke of the connecting rod Hi. This form of control of the eccentric l5 permits of a selected manual control of the length of stroke of the connecting rod which may be varied or changed at will to suit the whim of the engine operator. Upon the release of the oil pressure behind the centricity existent in the eccentric 6 and lengthplunger I 3, the plunger would be moved in a reverse direction by means of an expansion spring 23 confined within the cylinder I2, and the return movement of the plunger would rotate the eccentric I5 to whatever position the engine operator might desire for regulating the length of stroke of the connecting rod IS.

A suitable fluid pressure mechanism, not shown, would be used for generating a fluid pressure within the various passages and cylinders formed within the crank shaft, and the application of such pressure to be controlled by the conventional type of valves, not shown.

In the form of device shown in Fig. 7, we have provided a hollow crank throw 24 having the eccentric 25 rotatably mounted therearound. The cylinder 26 formed in the crank throw 24 has a plunger 21 slidably mounted thereon, and said plunger is provided with gear teeth 28 on the periphery thereof. An interior wall of the cylinder 26 is provided with a key slot 29 therein within which a pin 30 mounted on the plunger 21, is slidab-ly confined to prevent the plunger 21 from rotating. The eccentric 25 is provided with a gear segment 3| thereon, which extends through a slot in the throw 24, and said gear segment 3I is adapted to be engaged by the teeth 28 on the plunger 21.

In the form of device shown in Fig. '7, the eccentric 25 would be swung into any selected and predetermined position by centrifugal force caused by racing the engine, and then looking the eccentric in the desired position by engaging the gear segment 3! thereon with the teeth 28 of the plunger 21. The plunger 21 is moved axially in the cylinder 26 by means of fluid pressure directed into the cylinder 26 and against one face of the plunger 21, in the manner heretofore described in connection with Figs. 5 and 6. An expansion spring is confined in the cylinder 26, the purpose of said spring being to move the plunger 21 out of engagement with the gear segment 3| on the eccentric 25, when the fluid pressure against said plunger is released. In this form of the device the eccentric 25 is rotated into or out of any of its selected positions by centrifugal force created by either stepping up or slowing down the rotation of the engine crankshaft.

The form of device shown in Fig. '7 accomplishes a locking of the eccentric after the eccentric has been rotated by centrifugal force into any desired position, while with the form of device shown in Figs. 5 and. 6, the eccentric is moved mechanically into any selected position.

Having thus described this invention, what we claim and desire to secure by Letters Patent is:

An apparatus to vary the length of stroke of an engine connecting rod, including in combination a piston, a crank, a connecting rod therebetween, an eccentric sleeve interposed between the connecting rod-and crank shaft, adapted to vary the length of stroke of the connecting rod and piston by a turning movement of said sleeve relative to the crank shaft; a gear plunger reciprocatingly confined in said crank shaft; a toothed element on said eccentric sleeve engaging said gear plunger; a fluid pressure means for actuating said gear plunger to turn said eccentric sleeve about the crank shaft; and spring means for returning said gear plunger and for reversing the direction of movement of said eccentric sleeve upon the release of the fluid pressure.

GEORGE STERLING EDWARDS. JULIUS DUSEVOIR. 

